Discard requests for favicon.ico

Description

WP should not load in its entirety on favicon.ico requests, unless a plugin allows it to.

We should add the needed RewriteCond to the .htaccess statements. Or at the very least catch that sort of request early on (while we parse the request, for instance), apply filters in case a plugin wants to step in, and bail accordingly.

As things stand, every page load on a site without a favicon generates a 404 error that gets logged -- and on each of these, WP loads in its entirety, and hopelessly queries the database in an effort to canonically redirect to something that might work.